1. Field of the Invention
The present invention relates to a method of manufacturing a liquid crystal display (LCD) and an apparatus therefor, and more particularly, to a method of manufacturing an LCD and an apparatus for removing bubbles being formed between substrates and polarizing plates of a liquid crystal panel.
2. Description of the Related Art
An LCD comprises a liquid crystal panel which comprises a thin film transistor (TFT) substrate and a color filter substrate, the surfaces of which are respectively attached with polarizing plates, and a liquid crystal layer sandwiched between both substrates. Since the liquid crystal panel does not emit light itself, a backlight unit may be located behind the TFT substrate to supply light to the liquid crystal panel. The transmittance of light from the backlight unit depends on the alignment of the liquid crystal layer.
In addition, the LCD may further comprise a drive integrated circuit, a data driver and a gate driver to drive a pixel of the liquid crystal panel, wherein the data driver and the gate driver receive a driving signal from the drive integrated circuit and then apply a driving voltage on a data line and a gate line within display area respectively.
In the manufacturing process of the LCD, polarizing plates are attached to the outside plate surfaces of the TFT substrate and the color filter substrate. In this process, minute bubbles are formed between the substrates and the polarizing plates, thereby lowering the adhesion force therebetween and deteriorating display quality.
FIG. 1 is a perspective view showing a conventional bubble removing apparatus. The conventional bubble removing apparatus 100 comprises a chamber 110 and a door 120 which opens/closes the chamber 110. An accommodating part 130, in which liquid crystal panels 140 are loaded, is provided in the chamber 110. The bubble removing apparatus 100 further comprises a pump (not shown) to supply a compressed gas into the chamber 110, and a heater (not shown).
The method of removing the bubble using the above apparatus 100 will be explained.
First, the door 120 is opened to open the chamber 110. Then, the liquid crystal panels 140 are loaded into the accommodating part 130. At this time, the temperature and the pressure in the chamber 110 is room temperature and atmospheric pressure, respectively. The accommodating part 130 can be loaded with a plurality of liquid crystal panels 140 at the same time. The door 120 is shut to close the chamber 110 after the loading of liquid crystal panels 140 is completed.
Next, the temperature and the pressure are increased to predetermined levels. Generally, the temperature is increased to about 50° C., and the pressure is increased to about 5 kgf/cm2. By these operations, heat and pressure are applied to the liquid crystal panels 140 in the chamber 110. Therefore, the bubbles formed between the substrates and the polarizing plates are moved towards the outside of polarizing plates thereby to be removed. When the removing of the bubbles is completed, the temperature and the pressure in the chamber 110 are decreased to room temperature and atmospheric pressure, respectively. Then, the door 120 is opened to open the chamber 110, and the liquid crystal panels 140 are unloaded.
FIG. 2 is a graph showing the change of temperature and pressure in the chamber 110 of the conventional bubble removing apparatus.
Referring to FIG. 2, the ‘I’ section corresponds to the increase of temperature and pressure from room temperature and atmospheric pressure to predetermined values, which normally takes 8 minutes. The ‘II’ section corresponds to maintaining the temperature and the pressure at the predetermined values, which normally takes 15 minutes. The ‘III’ section corresponds to the restoration of the temperature and the pressure to room temperature and atmospheric pressure respectively, which normally takes 7 minutes.
The conventional method of removing bubbles has several disadvantages. First, it requires a significant amount of time in increasing and decreasing the temperature and the pressure of the chamber. Second, the chamber type apparatus is not suitable for treating a large liquid crystal panel. That is, it is difficult to manufacture a chamber which can accommodate a liquid crystal panel having a length greater than 1 m. Further, as the size of the chamber is increased, the safety of the chamber is not guaranteed with ease. Third, the presence of a chamber in a manufacturing process makes the automation of the process difficult.
Basically, these problems come from the presence of chamber in order to remove bubbles.